The general aim of this project is to investigate the role of phonological information in the organization and processing of words. This project will extend the behavioral and electrophysiological investigations of processing of auditory and phonetic input, conducted in the preceding projects, to the lexical levels. Children with specific language impairment (SLI) or with a history of chronic otitis media with effusion (OME) with a mild, fluctuating hearing loss share the common characteristic of having limitations or variations in auditory-phonetic input that are assumed to have an impact on the acquisition, representation, and processing of language. In this project, we will focus on the relation of the acoustic-phonetic form of a word to lexical representation, access and processing. The proposed project includes four sets of experiments, each employing a particular experimental paradigm. Experiment Set 1 examines the extent to which phonological features influence the ability to access the lexicon so as to differentiate words from non-words and open versus closed class words that differ along particular segmental dimensions, using a lexical decision task. Experiment Set 2 examines the speed of processing and the duration of retention of specific phonetic cues embedded in words, employing a match/mismatch to sample task. Experiment Set 3 examines the effects of lexical representation on category boundaries in a categorical perception task. Experiment Set 4 examines the effects of lexical representation on category boundaries to examine the extent to which phonological features of words (onset, rhyme) can affect the rapidity of lexical assess of a related word, using a primed lexical decision task. Twenty children (6;0-9-0) in each of the following groups will participate in the behavioral experiments: (1) SLI, (2) OMEplus, and (3) OMEplus (with normal language). Subjects for the electrophysiological experiments will be selected from these groups on the basis of their behavioral performance.